This invention relates to systems for supplying compressed air to spas and pools.
These air supply systems comprise a housing containing a motor and blower. In the prior art systems, the blower is typically of an axial impeller type, which is mounted above the motor. Air is drawn into the axial opening of the blower and is discharged downward through the motor, thereby providing air cooling for the motor. In such manner, the blower, driven by the motor, supplies compressed air to an air supply line, connected on one end to the motor/blower housing and on the other end to the spa. The compressed air is discharged through numerous small apertures in the wall of the spa, below the water level, thereby creating an effervescent effect.
In the prior art, the motor is located in a part of the housing which is in open communication with the air supply line. As a result, problems may arise when the air supply system is turned off. Since the air supply line is below the water level of the spa, water can flow back into this line. The momentum of the water may carry it beyond the air supply line to the housing, thereby risking water contact with the motor, and, thus, creating a hazard of shock and possible electrocution to the spa user.
These hazards are even more significant for spas equipped with water/air jets. In these installations, a water pump forces water through a pipe connected to the spa wall, thereby creating a water jet effect in the spa. However, it is often desirable to increase the turbulence of the existing water by introducing air into the water pipe near its outlet end. The air is typically supplied by a venturi which draws air into the water jet, but the turbulence may be increased by supplying the air under pressure from the same blower and motor used to produce the aforesaid effervescent effect.
Problems with these water/air jet systems occur if the spa user blocks the jet with his hand or other part of his body. Since the water is typically supplied at higher pressure than the air, the blockage may force water back through the air supply line to housing containing the blower and motor. Consequently, the motor is exposed to risk of short circuit. Since the spa user is necessarily in the water when this situation occurs, the short circuit creates an extreme danger of shock or electrocution.
The prior art has endeavored to minimize these dangers by use of check valves in the air line, and by raising the motor/blower housing, thereby increasing its height relative to the water level of the spa. These measures are somewhat successful in preventing the back flow of water into the motor/blower housing after the air supply has been turned off. They are less effective where the spa user has blocked the flow of the water/air jet. Their lack of effectiveness is due primarily to malfunctioning of the check valves, and to the aesthetic difficulties associated with increasing the height or the motor/blower housing. As a consequence, the prior art air supply systems expose spa users to a significant risk of shock and electrocution.
Another problem associated with the prior art relates to deterioration of the motors due to excessive humidity. Since the housing containing the blower and motor, or a pipe in open communication with this housing, can fill with water, the motor and associated electrical parts are exposed to dampness and moisture, even if the water level in the housing does not reach the motor. This moisture causes the motors to prematurely deteriorate, thereby increasing spa maintenance problems.